Automatic fever abatement applications

ABSTRACT

A method for treating fever by establishing a closed loop pathway to flow a treatment substance through a patient&#39;s body without the substance entering the patient&#39;s bloodstream, by engaging a fever characteristic sensor with the patient, by receiving a signal from such sensor and using the controller to control temperature and/or flow of the treatment substance.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation of U.S. patent applicationSer. No. 09/396,200 entitled Automatic Fever Abatement System, filed onSep. 15, 1999, the disclosures of which are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a system that abates fever inhospital patients by administering medication, coolant, or othertreatment substance.

[0004] 2. Description of the Related Art

[0005] In warm blooded creatures, temperature regulation is one of themost important functions of the body. The human body seeks to maintain acore temperature of 37 degrees Celsius, and functions optimally whenthis temperature is achieved. Excessive temperatures cause varioushealth problems, one of the most serious being brain damage. Forpatients with brain injury, fever can exacerbate neuronal outcomes.

[0006] To treat fever, a number of different techniques are known. Forexample, patients often receive medication such as acetaminophen(Tylenol) or acetylsalicylic acid (aspirin). In one extreme technique,physicians cool the patient's entire body by packing it in ice. Inanother technique, the patient is covered with a cooling blanket, suchas an inflatable cushion that is filled with a coolant such as air orwater. There are also other traditional approaches such a gastric lavagewith ice water, infusing cold solution, etc.

[0007] One newly developed approach treats fever by circulating acoolant through a catheter placed inside a patient's body. The cathetermay be inserted into veins, arteries, cavities, or other internalregions of the body. The present assignee has pioneered a number ofdifferent cooling catheters and techniques in this area. Severaldifferent examples are shown in U.S. application Ser. No. 09/133,813,which was filed on Aug. 13, 1998 and is hereby incorporated into thepresent application by reference.

[0008] Regardless of which technique is ultimately used to treat apatient's fever, each of these techniques is manually activated bymedical staff when they initially detect fever. Accordingly, someattention is required of medical staff in order to initially detect theonset of fever. This approach is therefore subject to some delay fromthe time medical staff recognize the start of fever until treatment isinitiated. Importantly, the delay in applying treatment is a missedopportunity to prevent the fever in the first place. Moreover, duringthis delay, the fever may proceed into more serious stages. Thus, thisdelay can represent some health risk to the patient. As the science ofmedicine is interested in minimizing or reducing health risks whereverpossible, the present Assignee realizes that known fever abatementapproaches may not be completely satisfactory.

SUMMARY OF THE INVENTION

[0009] Broadly, the present invention concerns a machine-driven systemto treat or even prevent fever in hospital patients by administeringmedication, coolant, or other treatment substance. One exemplary systemincludes a treatment substance administration path (“path”), a flowdevice, a source, one or more fever characteristic sensors, and acontroller. The path may be an open-ended structure, such as a tube, ora closed-ended structure such as a catheter with a sealed, internalconduit. The treatment substance administration path is coupled toregions of the patient's body that will contain or absorb the treatmentsubstance, as appropriate to the particular substance being used. Thepath is coupled to the flow device, which is itself attached to thesource. The flow device comprises a pump, valve, or other suitablemechanism to regulate flow of the treatment substance from the sourcethrough the path. The source contains a treatment substance such asmedication (in the case of an open-ended path) or a coolant (in the caseof a closed-ended path). One or more fever characteristic sensors areattached to various sites on the patient. In the case of a closed-endedpath, the system may also include a return vessel to receive treatmentsubstance returning from the patient's body.

[0010] The fever characteristic sensors repeatedly measure temperature,metabolic rate, and/or other bodily properties that are affected byfever, and provide representative machine-readable outputs.Concurrently, the controller repeatedly computes a supply strategy toregulate the patient's temperature according to pre-programmedspecifications. Then, according to the computed strategy, the controllerdirects the flow device to deliver treatment substance to the path, andultimately to the patient's body. In addition to administering coolant,medication, or other treatment substance to treat fever, the controllermay activate other antipyretic means by (1) starting, adjusting, orredirecting a fan, (2) adjusting an air conditioning thermostat, (3)issuing visual or audible warning signals to hospital staff, etc.

[0011] In one embodiment, the invention may be implemented to provide amethod to automatically treat or prevent fever in hospital patients byadministering medication, coolant, or other antipyretic treatmentsubstance. In another embodiment, the invention may be implemented toprovide an apparatus, such as fever abatement system, for automaticallytreating or preventing fever in hospital patients. In still anotherembodiment, the invention may be implemented to provide a signal-bearingmedium tangibly embodying a program of machine-readable instructionsexecutable by a digital data processing apparatus to perform operationsto manage components of an automatic fever abatement system. Anotherembodiment concerns logic circuitry having multiple interconnectedelectrically conductive elements configured to perform operations tomanage components of an automatic fever abatement system.

[0012] The invention affords its users with a number of distinctadvantages. In addition to quickly recognizing the presence or futureonset of fever, the invention automatically initiates a procedure tocool the patient. Unlike the prior art, there is no delay before medicalstaff recognize the start of fever. In fact, actions may be taken beforethe body even exhibits any temperature rise. With the invention, rapiddelivery of a therapeutic drug can begin within minutes from feverrecognition. As another benefit, the invention utilizes machine controlto minimize operator supervision, and thereby reduces operating costsand frees medical staff for other duties. Accordingly, the promptrecognition and treatment of fever no longer requires twenty-four hour,minute-by-minute attention from hospital staff and doctors. As stillanother advantage, fever detection characteristics may be customized foreach patient to ensure early and accurate fever detection. The inventionalso provides a number of other advantages and benefits, which should beapparent from the following description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1A is a schematic diagram of a fever abatement systemaccording to the invention.

[0014]FIG. 1B is a diagram of a closed-end treatment substanceadministration path according to the invention.

[0015]FIG. 1C is a diagram of an open-end treatment substanceadministration path according to the invention.

[0016]FIG. 2 is a diagram of a digital data processing apparatusaccording to the invention.

[0017]FIG. 3 shows an exemplary signal-bearing medium according to theinvention.

[0018]FIG. 4 is a flowchart of an operating sequence for automated feverabatement according to the invention.

DETAILED DESCRIPTION

[0019] The nature, objectives, and advantages of the invention willbecome more apparent to those skilled in the art after considering thefollowing detailed description in connection with the accompanyingdrawings.

[0020] Hardware Components & Interconnections

[0021] Automatic Fever Abatement System

[0022] Introduction

[0023] One aspect of the invention concerns a machine-driven system totreat or prevent fever in hospital patients by administering medication,coolant, or other antipyretic means. This system may be implemented invarious ways, one example being shown by the hardware components andinterconnections shown by the system 100 of FIG. 1. The system 100includes a controller 104, one or more fever characteristic sensors 106,a flow device 110, a treatment substance administration path 108, and asource 112. The system 100 is utilized to automatically treat or evenprevent fever in the patient 102.

[0024] Fever Characteristic Sensor(s)

[0025] As mentioned above, the system 100 includes one or more fevercharacteristic sensor(s) 106. As used herein, “fever” is defined asbodily temperature that is above normal due to pathogens or otherstimuli. The system of this invention may be configured to detect fever;more advantageously from the standpoint of preventing fever, theinvention may be configured to predictively detect the future onset offever. Utilizing the foregoing definition of fever, the presence offever is easily determined by detecting an elevated body temperature. Inthis respect, the fever characteristic sensors 106 may include one ormore temperature sensors, deployed in various regions of the body thataccurately represent the temperature of the entire body, the body core,or a particular region. As an example, a single temperature sensor maybe deployed at the esophagus, bladder, tympanic membrane, rectum, oranother local site that is representative of the body's coretemperature. With multiple temperature sensors, the sensors may bedistributed at various sites, and the resulting measurements averaged toprovide a more accurate representation of the patient's temperature.

[0026] Advantageously, the fever characteristic sensors 106 may alsoinclude other sensors to detect the onset of fever. Since fever ispreceded by increased metabolic rate, the sensors 106 may also includedevices to detect increased oxygen consumption, increased carbon dioxidein exhaled air, decreased venous hemoglobin oxygen saturation, and thelike. In the case of oxygen consumption or carbon dioxide measurement,the sensors 106 may comprise a gas analyzer coupled to automaticventilation equipment or an open mask apparatus. In the case of venoushemoglobin oxygen measurement, relevant sensors 106 may comprise opticallight reflectance and/or transmission devices, such as commerciallyavailable devices for detecting blood saturation.

[0027] Treatment Substance Administration Path

[0028] The treatment substance administration path 108 (“path”) providesa means to administer a treatment substance to the patient. The path 108may be open-end or closed-end. With an open-end path, the treatmentsubstance takes a one-way trip into a region of the patient's body thatis likely to absorb, distribute, or effectively process the treatmentsubstance. The open-end treatment substance administration path, forexample, may be routed to the patient's stomach, veins, arteries,esophagus, or rectum. The open-end path is advantageous for treatmentsubstances that comprise medication, such as acetaminophen, in whichcase an exemplary treatment substance administration path may comprise adevice such as nasogastric tube. FIG. 1C shows an exemplary open-endpath 140. The path 140 comprises a conduit having a body 146 with aninlet 142 and an outlet 144. The open-end treatment substanceadministration path 140 is deployed by inserting the outlet 144 into anartery, vein, stomach, rectum, skin, lungs or other suitable body accesspoint. Other examples of open-end path include a nasogastric tube,open-end catheter, intravenous needle, syringe, suppository, perforatedtube for “drip” irrigation, transdermal patch, aerosol or otherinhalant, etc.

[0029] In contrast to the open-end path, treatment substance circulateswithin the closed-end path without actually contacting the patient'sbody. This is beneficial if the treatment substance comprises a coolantsuch as saline. FIG. 1B shows an exemplary closed-end path 120, which isembodied by a cooling catheter. The catheter 120 includes a housing 122having distal 128 and proximal 130 ends. The housing 122 contains aconduit 123 that runs from the catheter's proximal end 130 to the distalend 128 and back again. The conduit 123 has a supply opening 126 and areturn opening 124. The conduit 123 therefore provides a round-trip pathinternal to the catheter 120, where this path is sealed from any contactwith the patient's body. The closed-end path 120 is deployed byinserting the distal end 128 into a suitable blood vessel such as theinferior vena cava. A number of exemplary catheters and their use aredescribed in U.S. application Ser. No. 09/321,515, which was filed onMay 27, 1999 and is hereby incorporated by reference into the presentapplication.

[0030] Flow Device, Source, Return Vessel

[0031] The flow device 110 controls flow of the treatment substance froma source 112 to the patient to help prevent or abate the patient'sfever. In one embodiment, the flow device 110 may comprise a pump orother structure that actively causes the treatment substance to flowthrough the path from the source 112, where the source comprises anintravenous bag, vial, jar, carton, box, or other storage facility. Inanother embodiment, the treatment substance flows by gravity and theflow device 110 comprises a valve, on-off switch, or other mechanism toregulate treatment substance flowing from the source 112. Here, thesource 112 may comprise any intravenous bag, vial, jar, carton, box, orother storage facility, whether compressible or not. In still anotherembodiment, the source 112 has a dynamic volume and the treatmentsubstance flows by reduction of the source's volume. Namely, the source112 may be a self-compressed vessel (e.g., distended elastic container),or a compressible vessel whose volume decreases under external force(e.g., syringe, hydraulic vessel, compressible intravenous bag, chamberwith piston-driven lid, etc.). In the case of a self-compressed source112, the flow device 110 comprises a solenoid or other suitable deviceto regulate the amount of flow through the path; in the case of anexternally compressed source 112, the flow device 110 comprises acompression mechanism such as a hydraulic pump, motor, piston, pinchers,screw-driven vise, etc. Ordinarily skilled artisans (having the benefitof this disclosure) will recognize a variety of other options toimplement the flow device 110 and source 112.

[0032] In the case of an open-end path, the flow device 110 regulatesflow of the treatment substance directly into the patient's body. In thecase of a closed-end path, the flow device 110 regulates flow of thetreatment substance into the supply opening (e.g., 126, FIG. 1B), andalso collects spent treatment substance from the catheter's returnopening (e.g., 124, FIGURE 1B). The flow device 110 deposits returnedtreatment substance into the return vessel 114. The return vessel 114may be omitted when an open-end path is used, or if the return vessel114 leads to, or is combined with, the source 112. When a closed-endpath is used, equipment for cooling the treatment substance may beimplemented at the source 112, the flow device 110, return vessel 114,or other suitable location. If desired, the path 108 may be configuredto incorporate one or more fever characteristic sensors 106. Forinstance, a rectal temperature probe may be combined with a pathdesigned for exposure or insertion of an antipyretic drug orsuppository.

[0033] Other Antipyretic Apparatus(es)

[0034] In addition to the foregoing components, the controller 104 maybe coupled to one or more additional controller-activated antipyreticapparatuses, whether related to the administration of treatmentsubstance or not. Some examples include inflatable cooling blankets,oscillating or fixed fans, air conditioning thermostats for room air orbath water, etc.

[0035] Controller-Generally

[0036] The controller 104 receives measurements from the sensor(s) 106,and serves to regulate operation of the flow device 110 according topredetermined specifications. To implement this automatic controlfeature, the controller 104 comprises an electronic module such as logiccircuitry, discrete circuit elements, or a digital data processingapparatus (computer) that executes a program of machine-readableinstructions.

[0037] When implemented in logic circuitry or a computer, the controller104 analyzes the patient's temperature and/or other fever characteristicsignals utilizing the controller's own programming, and provides theresultant output signal to regulate the flow device 110. Whenimplemented in discrete circuitry, the circuitry or the controller 104processes the patient's fever characteristics with circuitry to providea resultant output signal that regulates the flow device 110.

[0038] Controller-Digital Data Processing Apparatus

[0039] As mentioned above, one embodiment of the controller 104 is adigital data processing apparatus. This apparatus may be embodied byvarious hardware components and interconnections, one example appearingin FIG. 2. The apparatus 200 includes a processor 202, such as amicroprocessor or other processing machine, coupled to a storage 204. Inthe present example, the storage 204 includes a fast-access storage 206,as well as nonvolatile storage 208. The fast-access storage 206 maycomprise random access memory (RAM), and may be used to store theprogramming instructions executed by the processor 202. The nonvolatilestorage 208 may comprise, for example, one or more magnetic data storagedisks such as a “hard drive”, a tape drive, or any other suitablestorage device. The apparatus 200 also includes an input/output 210,such as a line, bus, cable, electromagnetic link, or other means for theprocessor 202 to exchange data with other hardware external to theapparatus 200.

[0040] Despite the specific foregoing description, ordinarily skilledartisans (having the benefit of this disclosure) will recognize that theapparatus discussed above maybe implemented in a machine of differentconstruction, without departing from the scope of the invention. As aspecific example, one of the components 206, 208 may be eliminated;furthermore, the storage 204 may be provided on-board the processor 202,or even provided externally to the apparatus 200.

[0041] Controller-Logic Circuitry

[0042] In contrast to the digital data storage apparatus discussedpreviously, a different embodiment of the invention implements thecontroller 104 with logic circuitry instead of computer-executedinstructions. Depending upon the particular requirements of theapplication in the areas of speed, expense, tooling costs, and the like,this logic may be implemented by constructing an application-specificintegrated circuit (ASIC) having thousands of tiny integratedtransistors. Such an ASIC may be implemented using CMOS, TTL, VLSI, oranother suitable construction. Other alternatives include a digitalsignal processing chip (DSP), discrete circuitry (such as resistors,capacitors, diodes, inductors, and transistors), field programmable gatearray (FPGA), programmable logic array (PLA), and the like.

[0043] Operation

[0044] In addition to the structure described above, a different aspectof the invention concerns a process for automated fever abatement. Asillustrated below, this process includes steps that are manuallyperformed, such as preparing the patient for treatment. The process alsoincludes automatic, machine-activated steps that treat or even preventthe patient's fever.

[0045] Signal-Bearing Medium

[0046] In the context of FIGS. 1-2, the automated fever abatementprocess may be implemented, for example, by operating the controller104, as embodied by a digital data processing apparatus 200, to executea sequence of machine-readable instructions. These instructions mayreside in various types of signal-bearing media. In this respect, oneaspect of the present invention concerns a programmed product,comprising signal-bearing media tangibly embodying a program ofmachine-readable instructions executable by a digital data processor tooperate the system 100 to perform automated fever abatement.

[0047] This signal-bearing media may comprise, for example, RAM (notshown) contained within the controller 104, as represented by thefast-access storage 206, for example. Alternatively, the instructionsmay be contained in another signal-bearing media, such as a magneticdata storage diskette 300 (FIG. 3), directly or indirectly accessible bythe processor 202. Whether contained in the diskette 300, storage 204,or elsewhere, the instructions may be stored on a variety ofmachine-readable data storage media, such as direct access storage(e.g., a conventional “hard drive,” redundant array of inexpensive disks(RAID), or another direct access storage device (DASD)), magnetic tape,electronic read-only memory (e.g., ROM, EPROM, or EEPROM), opticalstorage (e.g., CD-ROM, WORM, DVD, digital optical tape), paper “punch”cards, or other suitable signal-bearing media including transmissionmedia such as digital and analog and communication links and wireless.In an illustrative embodiment of the invention, the machine-readableinstructions may comprise software object code, compiled from a languagesuch as “C,” etc.

[0048] Logic Circuitry

[0049] In contrast to the signal-bearing medium discussed above, themethod of automated fever abatement may be implemented using logiccircuitry, without using a processor to execute instructions. In thisembodiment, the logic circuitry is implemented in the controller 104,and serves to perform an operational sequence according to thisinvention as described below. The logic circuitry may be implementedusing many different types of circuitry, as discussed above.

[0050] Overall Sequence of Operation

[0051]FIG. 4 shows a sequence 400 that illustrates one example of themethod aspect of the present invention. For ease of explanation, butwithout any intended limitation, the example of FIG. 4 is described inthe context of FIGS. 1-2, as described above. After the sequence 400 isinitiated in step 402, medical staff prepare the patient for treatment(step 404). As an example, such preparation may involve bathing,shaving, dressing, and other activities. Next, medical staffinterconnect the components of the system 100 and deploy the path 108 tothe appropriate bodily site(s) (step 406). Alternatively, if the system100 components are pre-assembled, the assembly steps are omitted. Afterstep 406, medical staff deploy the fever characteristic sensor(s) 106 attarget regions of the patient's body. Upon completion of step 406, thesensors begin to measure the relevant physiological characteristics andprovide representative machine-readable outputs.

[0052] As illustrated, steps 404,406, and 408 are performed manually. Asdescribed below, however, steps 409, 410, 412, and 414 are performed bythe controller 104 and serve to implement an automated method of feverabatement. In step 409, the controller 104 collects input for use indeciding how to operate the flow device 110 and thereby regulate thepatient's temperature. Among other possible input, the input of step 409includes input from the sensor(s) 106, such as body temperature,metabolic rate, and other bodily characteristics affected by fever. Theinput may also include other information such as (1) whether the path108 is closed-end or open-end, (2) if the path 108 is open-end, thestrength of the medication that constitutes the treatment substance, (3)the volume output of the flow device 110, (4) the patient's temperaturehistory, (5) the history of treatment substance application with thecurrent patient, (6) any post-delivery time delay required for treatmentsubstance to take effect, and (7) other such factors.

[0053] After step 409, the controller computes a supply strategy in step410. The supply strategy specifies a volume, timing, and rate oftreatment substance supply that is calculated to regulate the patient'stemperature according to predetermined specifications. Thesepredetermined specifications are pre-programmed into the controller 104.As an example, the predetermined specifications may dictate keeping thepatient's core temperature at or below 37.5 degrees Celsius, limitingany temperature excursions to a maximum time or temperature, etc.

[0054] Thus, the supply strategy constitutes the manner of treatmentsubstance delivery that will achieve the predetermined specifications.To compute the supply strategy, the controller 104 considers the inputfrom step 409 and applies a predetermined analysis to this data. Thepredetermined analysis may be specified by one or more equations, lookuptables, or other machine-readable information available to thecontroller 104 by software programming, hardware configuration, etc.

[0055] To illustrate step 410 in greater detail some examples areprovided. In a first example, the path 108 is closed-end and thetreatment substance comprise room temperature or cooled saline, and thepredetermined specifications require keeping the patient's coretemperature below 37.5 degrees Celsius. Here, one example of thecontroller's strategy is (1) operating the flow device 110 to circulatecoolant if the patient's temperature reaches 37.5 degrees Celsius, and(2) ceasing operation of the flow device 110 whenever the patient'stemperature is below 37.5 degrees Celsius.

[0056] In a second example, the path 108 is open-end and the treatmentsubstance comprises one or more antipyretic drugs such as acetaminophen,aspirin, naproxen, ibuprofen, etc. In this example, the controller 104may compute a strategy that activates the flow device 110 to administera bolus of the treatment substance upon detecting fever or febral onset.Bolus may be especially desirable because fever tends to occur in spikeswith rapid onset, and rapid initial delivery in a bolus may rapidlyestablish a meaningful blood concentration of the antipyretic treatmentsubstance.

[0057] As an alternative strategy, an initial bolus of one drug may beadministered, and if fever persists, a second larger bolus of the samedrug or a bolus of a second antipyretic drug is administered.Furthermore, once fever is detected (or febral inset predicted), thetreatment substance may be administered with an increasing rate if apreset body temperature is reached or if a predetermined rate oftemperature increase is detected.

[0058] After the supply strategy is computed in step 410, the controller104 directs the administration equipment 100 to implement this strategyin step 412. Namely, the controller 104 directs the flow device 110 tobegin delivering the treatment substance to the path 108 according tothe computed supply strategy. Where the flow device 110 comprises avalve, step 412 involves opening, closing, or adjusting constriction ofthe valve. Where the flow device 110 is a pump, the flow rate may becontrolled by varying pump speed or repeatedly turning a constant-speedpump on and off. Also in step 412, the controller 104 may record thetime that treatment began for subsequent documentation by nurses, etc.

[0059] In step 414, the controller 104 determines whether it hasreceived an “off” command. The “off” command may be received by keyboardentry, manual activation of a switch (not shown) coupled to thecontroller 104, expiration of a pre-programmed treatment period, etc. Ifthe “off” command has not been received, the sequence 400 returns tostep 409, whereupon the controller 104 receives further input from thesensors 106, adjusts the supply strategy if necessary (step 410), anddirects the components of the system 100 accordingly (step 412). Whenstep 414 receives the “off” command, the routine 400 ends in step 416.

[0060] Other Embodiments

[0061] While the foregoing disclosure shows a number of illustrativeembodiments of the invention, it will be apparent to those skilled inthe art that various changes and modifications can be made hereinwithout departing from the scope of the invention as defined by theappended claims. Furthermore, although elements of the invention may bedescribed or claimed in the singular, the plural is contemplated unlesslimitation to the singular is explicitly stated.

What is claimed is:
 1. A method for treating fever comprising:establishing a pathway for fluid communication for a treatment substanceto flow in a closed loop through a patient's body without entering thebloodstream; engaging at least one fever characteristic sensor with thepatient; receiving signals from the sensor at a controller; using thecontroller to control at least one of: temperature, and flow, of thetreatment substance to counter fever in the patient.
 2. The method ofclaim 1, wherein the controller counters fever by alleviating fever oncethe sensor indicates that the patient is febrile.
 3. The method of claim1, wherein the controller counters fever by prophylactically preventinga febrile episode.